Liquid chromatography is a form of chromatography used frequently in biochemistry and analytical chemistry to separate, identify, and quantify compounds based on their properties such as polarity and their interactions with a stationary phase. Liquid chromatography can be performed using planar or column techniques. In both cases, the system includes a chromatographic device with a stationary phase, a means for moving a mobile phase (solvent carrying compounds of interest) through the device (such as a pump, or gravity), and a detector that creates a signal to identify a particular compound based on the time of the signal and the amount of the compound based on the intensity of the signal. The detector may also provide other characteristic information (e.g. UV/Vis spectroscopic data for a compound if so equipped). The detector may also be a mass spectrometer. Retention time of a compound in the device varies depending on the strength of the compound's interactions with the stationary and mobile phases, the ratio/composition of the mobile phase that is used, and the flow rate of the mobile phase.
The composition of the mobile phase flowing through the chromatographic device is critical to obtaining the required separation of compounds. For example, in reversed-phase chromatography, it can be useful to adjust the pH of the mobile phase to control the selectivity and resolution of the chromatographic separation. Small increments of pH change can have significant impact on the effectiveness and suitability of the chromatographic separation. However, manual preparation of the numerous acid and base buffer solutions for such analyses is time consuming and error-prone. Prior art systems have allowed users to blend multiple solvents to create mobile phases of particular pH. However, in these systems the user was required to know not only the pH of their particular solvents, but also the pH that would result from mixing the solvents in various proportions. It would be desirable to have a system and method for automatically calculating and blending buffer solutions and the organic and aqueous mobile phase componentsto produce a particular pHspecified by a user, and for varying the proportions of buffer and solvents over the course of the elution. It would also be desirable to have buffer solutions and mobile phase combinations that are compatible with reversed-phase mass spectrometry over a large pH range.